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  This medicinal product is subject to additional monitoring. This will allow quick identification of new safety information. Healthcare professionals are asked to report any suspected adverse reactions. See section 4.8 for how to report adverse reactions.

1. Name of the medicinal product

CRYSVITA 10 mg solution for injection

CRYSVITA 20 mg solution for injection

CRYSVITA 30 mg solution for injection

2. Qualitative and quantitative composition

CRYSVITA 10 mg solution for injection

Each vial contains 10 mg of burosumab in 1 ml solution.

CRYSVITA 20 mg solution for injection

Each vial contains 20 mg of burosumab in 1 ml solution.

CRYSVITA 30 mg solution for injection

Each vial contains 30 mg of burosumab in 1 ml solution.

Burosumab is a recombinant human monoclonal IgG1 antibody for FGF23 and is produced by recombinant DNA technology using Chinese hamster ovary (CHO) mammalian cell culture.

Excipient with known effect

Each vial contains 45.91 mg sorbitol.

For the full list of excipients, see section 6.1.

3. Pharmaceutical form

Solution for injection (injection).

Clear to slightly opalescent, colourless to pale brownish-yellowish solution.

4. Clinical particulars
4.1 Therapeutic indications

CRYSVITA is indicated for the treatment of X-linked hypophosphataemia with radiographic evidence of bone disease in children 1 year of age and older and adolescents with growing skeletons.

4.2 Posology and method of administration

Treatment should be initiated by a physician experienced in the management of patients with metabolic bone diseases.


Oral phosphate and vitamin D analogues should be discontinued 1 week prior to initiation of treatment. At initiation, fasting serum phosphate concentration should be below the reference range for age (see section 4.3).

The recommended starting dose is 0.4 mg/kg of body weight and the normal maintenance dose is 0.8 mg/kg burosumab given every two weeks. The maximum dose is 90 mg. All doses should be rounded to the nearest 10 mg.

After initiation of treatment with burosumab, fasting serum phosphate should be measured every 2 weeks for the first month of treatment, every 4 weeks for the following 2 months and thereafter as appropriate. Fasting serum phosphate should also be measured 4 weeks after any dose adjustment. If fasting serum phosphate is within the reference range for age, the same dose should be maintained.

To decrease the risk for ectopic mineralisation, it is recommended that fasting serum phosphate is targeted in the lower end of the normal reference range for age (see section 4.4).

Dose increase

If fasting serum phosphate is below the reference range for age, the dose may be increased stepwise by 0.4 mg/kg up to a maximum dose of 2.0 mg/kg (maximum dose of 90 mg). Fasting serum phosphate should be measured 4 weeks after dose adjustment. Burosumab should not be adjusted more frequently than every 4 weeks.

Dose decrease

If fasting serum phosphate is above the reference range for age, the next dose should be withheld and the fasting serum phosphate reassessed within 4 weeks. The patient must have fasting serum phosphate below the reference range for age to restart burosumab at approximately half of the previous dose.

Missed dose

If a patient misses a dose, burosumab should be resumed as soon as possible at previously prescribed dose.

Special populations

Renal impairment

Burosumab has not been studied in patients with renal impairment. Burosumab must not be given to patients with severe or end stage renal disease (see section 4.3).

Paediatric population

The safety and efficacy of burosumab in children aged less than one year have not been established. No data are available.

Method of administration

For subcutaneous use.

Burosumab should be injected in the arm, abdomen, buttock or thigh. The maximum volume of medicinal product per injection site is 1.5 ml. If more than 1.5 ml is required on a given dosing day, the total volume of medicinal product should be split and should be administered at two different injection sites. Injections sites should be rotated and carefully monitored for signs of potential reactions (see section 4.4).

For handling of burosumab before administration, see section 6.6.

4.3 Contraindications

Hypersensitivity to the active substance or to any of the excipients listed in section 6.1.

Concurrent administration with oral phosphate, vitamin D analogues (see section 4.5).

Fasting serum phosphate above the normal range for age due to the risk of hyperphosphatemia (see section 4.4).

Patients with severe renal impairment or end stage renal disease.

4.4 Special warnings and precautions for use

Ectopic mineralisation

Ectopic mineralisation, as manifested by nephrocalcinosis, has been observed in patients with XLH treated with oral phosphorous and vitamin D analogues; these medicinal products should be stopped at least 1 week prior to initiating burosumab treatment (see section 4.2).

Monitoring for signs and symptoms of nephrocalcinosis, e.g. by renal ultrasonography, is recommended at the start of treatment and every 6 months for the first 12 months of treatment, and annually thereafter. Monitoring of plasma alkaline phosphatases, Calcium, PTH and creatinine is recommended every 6 months (every 3 months for children 1- 2 years) or as indicated.

Monitoring of urine calcium and phosphate is suggested every 3 months.


Patient's fasting serum phosphate level should be monitored due to the risk of hyperphosphatemia. To decrease the risk for ectopic mineralisation, it is recommended that fasting serum phosphate is targeted in the lower end of the normal reference range for age. Dose interruption and/or dose reduction may be required (see section 4.2). Periodic measurement of post prandial serum phosphate is advised.

Serum parathyroid hormone

Increases in serum parathyroid hormone have been observed in some XLH patients during treatment with burosumab. Periodic measurement of serum parathyroid hormone is advised.

Injection site reactions

Administration of burosumab may result in local injection site reactions. Administration should be interrupted in any patient experiencing severe injection site reactions (see section 4.8) and appropriate medical therapy administered.


Burosumab must be discontinued if serious hypersensitivity reactions occur and appropriate medical treatment should be initiated.

Excipient with known effect

This medicine contains 45.91 mg of sorbitol in each vial which is equivalent to 45.91 mg/ml.

4.5 Interaction with other medicinal products and other forms of interaction

Concurrent administration of burosumab with oral phosphate and vitamin D analogues is contraindicated as it may cause an increased risk of hyperphosphatemia and hypercalcaemia (see section 4.3).

Caution should be exercised when combining burosumab with calcimimetic medicinal products (i.e. agents that mimic the effect of calcium on tissues by activating the calcium receptor). Co-administration of these medicinal products has not been studied in clinical trials and could potentially exacerbate hypocalcaemia.

4.6 Fertility, pregnancy and lactation


There are no or limited amount of data from the use of burosumab in pregnant women.

Studies in animals have shown reproductive toxicity (see section 5.3).

CRYSVITA is not recommended during pregnancy and in women of childbearing potential not using contraception.


It is unknown whether burosumab/metabolites are excreted in human milk.

A risk to newborns/infants cannot be excluded.

A decision must be made whether to discontinue breast-feeding or to discontinue/abstain from CRYSVITA therapy taking into account the benefit of breast feeding for the child and the benefit of therapy for the woman.


Studies in animals have shown effects on male reproductive organs (see section 5.3). There are no clinical data available on the effect of burosumab on human fertility. No specific fertility studies in animals with burosumab were conducted.

4.7 Effects on ability to drive and use machines

Burosumab may have a minor influence on the ability to drive and use machines. Dizziness may occur following administration of burosumab.

4.8 Undesirable effects

Summary of the safety profile

The most common adverse drug reaction (ADR) reported in paediatric patients up to 64 weeks was injection site reactions (57%), headache (54%), pain in extremity (42%), vitamin D decreased (28%), rash (23%), toothache (19%), tooth abscess (14%), myalgia (14%), and dizziness (11%) (See section 4.4 and 'Description of selected adverse reactions' below).

Tabulated list of adverse reactions

Table 1 gives the adverse reactions observed from clinical trials. The adverse reactions are presented by system organ class and frequency categories, defined using the following convention: very common (≥1/10); common (≥1/100 to <1/10); uncommon (≥1/1000 to <1/100); rare (≥1/10,000 to <1/1000); very rare (<1/10,000), not known (cannot be estimated from the available data). Within each frequency grouping, undesirable effects are presented in order of decreasing seriousness.

Table 1: Adverse reactions reported in paediatric patients with XLH (N=65)

MedDRA System Organ Class

Frequency category

Adverse reaction

Infections and infestations

Very common

Tooth abscess

Nervous system disorder

Very common


Very common


Gastrointestinal Disorders

Very common


Skin and subcutaneous tissue disorder

Very common


Musculoskeletal and connective tissue disorders

Very common


Very common

Pain in extremity

General disorders and administration site conditions

Very common

Injection site reaction


Very common

Vitamin D decreased

Description of selected adverse reactions

Injection site reactions

Local reactions (e.g. injection site urticaria, erythema, rash, swelling, bruising, pain, pruritus, and haematoma) have occurred at the site of injection. In the paediatric studies, approximately 57% of the patients had an injection site reaction. The injection site reactions were generally mild in severity, occurred within 1 day of medicinal product administration, lasted approximately 1 to 3 days, required no treatment, and resolved in almost all instances.

Skin reactions

In paediatric patients, the most frequent potential hypersensitivity events were rash (22%), injection site rash (6%), and urticaria (4%). The events were mild or moderate in severity.


Anti-drug antibodies (ADA) have been detected in a small percentage of patients receiving burosumab who had also tested positive for ADA prior to dosing; no adverse events or loss of efficacy was associated with these findings.

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme Website: or search for MHRA Yellow Card in the Google Play or Apple App Store.

4.9 Overdose

There is no experience with overdose of burosumab. Burosumab has been administered in paediatric clinical trials without dose limiting toxicity using doses up to 2.0 mg/kg body weight with a maximal dose of 90 mg every two weeks. In adult clinical trials no dose limiting toxicity has been observed using doses up to 1.0 mg/kg or a maximal total dose of 128 mg every 4 weeks.


In case of overdose, it is recommended to stop burosumab and to monitor biochemical response.

5. Pharmacological properties
5.1 Pharmacodynamic properties

Pharmacotherapeutic group: Drugs for the treatment of bone diseases, other drugs affecting bone structure and mineralisation, ATC code: M05BX05.

Mechanism of action

Burosumab is a recombinant human monoclonal antibody (IgG1) that binds to and inhibits the activity of fibroblast growth factor 23 (FGF23). By inhibiting FGF23, burosumab increases tubular reabsorption of phosphate from the kidney and increases serum concentration of 1, 25 dihydroxy-Vitamin D.

Clinical efficacy and safety

Study UX023-CL201

In paediatric Study UX023-CL201, 52 paediatric patients aged 5 to 12 years (mean 8.5 years; SD 1.87) with XLH were treated for 64 weeks. Nearly all patients had radiographic evidence of rickets at baseline and had received prior oral phosphate and vitamin D analogues for a mean (SD) duration of 7 (2.4) years. This conventional therapy was discontinued 2-4 weeks prior to burosumab initiation. The burosumab dose was adjusted to target a fasting serum phosphorous concentration of 1.13 to 1.62 mmol/L. Twenty six of 52 patients received burosumab every 4 weeks (Q4W). Twenty six of 52 patients received burosumab every two weeks (Q2W) at an average dose (min, max) of 0.73 (0.3, 1.5), 0.98 (0.4, 2.0) and 1.04 (0.4, 2.0) mg/kg at weeks 16, 40 and 60 respectively, and up to a maximum dose of 2.0 mg/kg.

Burosumab increased serum phosphate concentration and increased TmP/GFR). Changes in serum phosphate concentration over time are shown in Figure 1. In the group that received burosumab every 2 weeks, mean (SD) serum phosphate concentration increased from 0.77 (0.13) mmol/L at baseline, to 1.07 (0.13) mmol/L at Week 40 and was maintained to Week 64 at 1.08 (0.14) mmol/L.

Figure 1: Serum Phosphate Concentration (mmol/L) over Time in the Phase 2 Paediatric Study in Children 5-12 years Receiving Burosumab Every 2 Weeks (Q2W)

Serum alkaline phosphatase activity

Mean (SD) serum total alkaline phosphatase activity was 459 (105) U/L at baseline and decreased to 369 (76) U/L at Week 64 (-19.6%, p < 0.0001).

Bone-derived serum alkaline phosphatase content was 165 (52) μg/L [mean (SD)] at Baseline and 115 (31) μg/L at Week 64 (mean change: -28.5%).

Rickets Severity Score (RSS)

The severity of paediatric rickets in Study UX023-CL201 was measured using the RSS, a radiographic scoring method developed originally to assess the severity of nutritional rickets in the wrists and knees based on the degree of metaphyseal fraying, concavity, and the proportion of the growth plate affected. In Study UX023-CL201, the RSS was scored using a predefined scale looking at specific abnormalities in the wrists and knees. Results are summarised in table 2. The negative change in the Rickets Severity Score reflects resolution of the x-ray appearance of rickets.

Radiographic Global Impression of Change (RGI-C)

As a complement to the RSS system to assess the severity of paediatric rickets in Study UX023CL201, the RGI-C is a relative rating scale that compares a patient's rickets before and after treatment utilising a 7-point ordinal scale to evaluate change in the same abnormalities rated in the RSS. Scores range from -3 (indicating severe worsening of rickets) to +3 (indicating complete healing of rickets). Results are summarised in Table 2. The positive change in the RGI-C score reflects resolution of the x-ray appearance of rickets.

Table 2: Rickets Response in Children 5-12 years Receiving Burosumab in Study UX023-CL201


Duration of Burosumab


Effect Size

Q2W (N=26)

Q4W (N=26)

RSS Total Score

Baseline Mean (SD)

LS Mean change (SE) from baseline in total scorea (reduced RSS score indicates improvement in rickets severity)






1.92 (1.2)

-1.06 (0.1) (p<0.0001)

-1.00 (0.1) (p<0.0001)


1.67 (1.0)

-0.73 (0.1) (p<0.0001)

-0.84 (0.1) (p<0.0001)

RGI-C Global Score

LS Mean score (SE)a (positive indicates healing)





+1.66 (0.1) (p<0.0001)

+1.56 (0.1) (p<0.0001)


+1.47 (0.1) (p<0.0001)

+1.58 (0.1) (p<0.0001)

a) The estimates of LS means and p-values are from the generalized estimation equation model accounting for baseline RSS, visits and regimen and its interaction.

Genu varum inter-condylar distance and genu valgum inter-malleolar distance did not change from Baseline up to Week 64.

Study UX023-CL205

In paediatric Study UX023-CL205, burosumab was evaluated in 13 XLH patients, aged 1 to 4 years (mean 2.9 years; SD 1.1) for 40 weeks. All patients had radiographic evidence of rickets at baseline and twelve patients had received oral phosphate and vitamin D analogues for a mean (SD) duration of 16.7 (14.4) months. This conventional therapy was discontinued 2-6 weeks prior burosumab initiation. Patients received burosumab at a dose of 0.8 mg/kg every two weeks.

In Study UX023-CL205, mean (SD) fasting serum phosphate concentration increased from 0.81 (0.092) mmol/L at baseline to 1.12 (0.158) mmol/L at Week 40.

Serum alkaline phosphatase activity

Mean (SD) serum total alkaline phosphatase activity was 549 (193.8) U/L at baseline and decreased to 335 (87.6) U/L at Week 40 (mean change: -36.3%).

Rickets Severity Score (RSS)

After 40 weeks of treatment with burosumab, mean total RSS improved from 2.92 (1.367) at baseline to 1.19 (0.522), corresponding to a change from baseline in LS mean (SE) change of -1.73 (0.132) (p<0.0001).

Radiographic Global Impression of Change (RGI-C)

After 40 weeks of treatment with burosumab, the LS mean (SE) RGI-C Global score was +2.33 (0.08) in all 13 patients (p < 0.0001) demonstrating healing of rickets. All 13 patients were considered RGI-C responders as defined by RGI-C global score ≥ +2.0.

The European Medicines Agency has deferred the obligation to submit the results of studies with CRYSVITA in one or more subsets of the paediatric population in treatment of X-linked hypophosphataemia. See 4.2 for information on paediatric use.

This medicinal product has been authorised under a so-called 'conditional approval' scheme. This means that further evidence on this medicinal product is awaited.

The European Medicines Agency will review new information on this medicinal product at least every year and this SmPC will be updated as necessary.

5.2 Pharmacokinetic properties


Burosumab absorption from subcutaneous injection sites to blood circulation is nearly complete. Following subcutaneous administration, the time to reach maximum serum concentrations (Tmax) of burosumab is approximately 5-10 days. The peak serum concentration (Cmax) and area under the concentration-time curve (AUC) of serum burosumab is dose proportional over the dose range of 0.1-2.0 mg/kg.


In XLH patients, the observed volume of distribution of burosumab approximates the volume of plasma, suggesting limited extravascular distribution.


Burosumab is composed solely of amino acids and carbohydrates as a native immunoglobulin and is unlikely to be eliminated via hepatic metabolic mechanisms. Its metabolism and elimination are expected to follow the immunoglobulin clearance pathways, resulting in degradation to small peptides and individual amino acids.


Due to its molecular size, burosumab is not expected to be directly excreted. The clearance of burosumab is dependent on body weight and estimated to be 0.290 L/day and 0.136 L/day in a typical adult (70 kg) and paediatric (30 kg) XLH patient, respectively, with corresponding disposition half-life (t1/2) in the serum of approximately 19 days.


Burosumab displays time-invariant pharmacokinetics that is linear to dose over the subcutaneous dose range of 0.1 to 2.0 mg/kg.

Pharmacokinetic/pharmacodynamic relationship(s)

With the subcutaneous route of administration, a direct PK-PD relationship between serum burosumab concentrations and increases in serum phosphate concentration is observed and well described by an Emax/EC50 model. Serum burosumab and phosphate concentrations, as well as TmP/GFR, increased and decreased in parallel and reached maximum levels at approximately the same time point after each dose, supporting a direct PK-PD relationship. The AUC for the change from baseline in serum phosphate, TmP/GFR and 1,25(OH)2D increased linearly with increasing burosumab AUC.

Paediatric PK/PD

No significant difference has been observed in paediatric patient pharmacokinetics or pharmacodynamics as compared with PK/PD in the adult population. Burosumab clearance and volume of distribution are body weight dependent.

5.3 Preclinical safety data

Adverse reactions in non-clinical studies with normal animals were observed at exposures which resulted in serum phosphate concentration greater than normal limits. These effects were consistent with an exaggerated response to the inhibition of normal FGF23 levels resulting in a supraphysiologic increase in serum phosphate beyond the upper limit of normal.

Studies in rabbits and adult and juvenile cynomolgus monkeys demonstrated dose-dependent elevations of serum phosphate and 1,25 (OH)2D confirming the pharmacologic actions of burosumab in these species. Ectopic mineralisation of multiple tissues and organs (e.g. kidney, heart, lung, and aorta), and associated secondary consequences (e.g. nephrocalcinosis) in some cases, due to hyperphosphataemia, was observed in normal animals at doses of burosumab that resulted in serum phosphate concentrations in animals greater than approximately 2.58 mmol/L. In a murine model of XLH, a significant reduction in the incidence of ectopic mineralisation was observed at equivalent levels of serum phosphate, suggesting that the risk of mineralisation is less in the presence of excess FGF23.

Bone effects seen in adult and juvenile monkeys included changes in bone metabolism markers, increases in thickness and density of cortical bone, increased density of total bone and thickening of long bone. These changes were a consequence of higher than normal serum phosphate levels, which accelerated bone turnover and also led to periosteal hyperostosis and a decrease in bone strength in adult animals, but not in juvenile animals at the doses tested. Burosumab did not promote abnormal bone development, as no changes in femur length or bone strength were noted in juvenile animals. Bone changes were consistent with the pharmacology of burosumab and the role of phosphate in bone mineralization, metabolism and turnover.

In repeat-dose toxicology studies of up to 40 weeks duration in cynomolgus monkeys, mineralisation of the rete testis/seminiferous tubules was observed in male monkeys; however, no changes were observed in semen analysis. No adverse effects on female reproductive organs were observed in these studies.

In the reproductive and developmental toxicology study performed in pregnant cynomolgus monkeys, moderate mineralisation of the placenta was seen in pregnant animals given 30 mg/kg of burosumab and occurred in animals with peak serum phosphate concentration greater than approximately 2.58 mmol/L. Shortening of the gestation period and associated increased incidence of premature births were observed in pregnant monkeys at doses of ≥ 0.3 mg/kg which corresponded to burosumab exposures that are ≥0.875- to 1.39-fold anticipated clinical levels. Burosumab was detected in serum from fetuses indicating that burosumab was transported across the placenta to the fetus. There was no evidence of teratogenic effects. Ectopic mineralisation was not observed in foetuses or offspring and burosumab did not affect pre- and postnatal growth including survivability of the offspring.

In preclinical studies, ectopic mineralisation has been observed in normal animals, most frequently in the kidney, given burosumab at doses that resulted in serum phosphate concentrations greater than 2.58 mmol/L (see section 5.3). Neither new or clinically meaningful worsening of nephrocalcinosis nor ectopic mineralisation have been observed in clinical trials of patients with XLH treated with burosumab to achieve normal serum phosphate levels.

6. Pharmaceutical particulars
6.1 List of excipients


D-sorbitol E420

Polysorbate 80


Hydrochloric acid, 10% (for pH adjustment)

Water for injections

6.2 Incompatibilities

In the absence of compatibility studies, this medicinal product must not be mixed with other medicinal products.

6.3 Shelf life

2 years.

6.4 Special precautions for storage

Store in a refrigerator (2°C to 8°C). Do not freeze.

Store in the original package in order to protect from light.

6.5 Nature and contents of container

Clear glass vial with butyl rubber stopper, and aluminium seal.

Pack size of one vial.

6.6 Special precautions for disposal and other handling

Each vial is for single use only.

Do not shake the vial before use.

Burosumab should be administered using aseptic technique and sterile disposable syringes and injection needles.

Any unused medicinal product or waste material should be disposed of in accordance with local requirements.

7. Marketing authorisation holder

Kyowa Kirin Holdings B.V.

Bloemlaan 2

2132NP Hoofddorp

The Netherlands

8. Marketing authorisation number(s)




9. Date of first authorisation/renewal of the authorisation

Date of first authorisation: 19 February 2018

Date of latest renewal: 21 February 2019

10. Date of revision of the text


Detailed information on this medicinal product is available on the website of the European Medicines Agency